S1223翼型俯仰-沉浮运动的非定常气动特性分析  

Numerical study of the phunging-pitching motion of S1223 airfoil

作　　者：常兴华[1,2] 马戎[2] 张来平[1,2] 赫新[2] 

机构地区：[1]中国空气动力研究与发展中心空气动力学国家重点实验室,四川绵阳621000 [2]中国空气动力研究与发展中心计算空气动力研究所,四川绵阳621000

出　　处：《空气动力学学报》2017年第1期62-70,共9页Acta Aerodynamica Sinica

基　　金：国家自然科学基金(11532016;11672324);国家重点研发计划(2016YFB0200701)

摘　　要：扑翼飞行器是未来航空领域的重要发展方向之一,而鸟类、昆虫等自然界的飞行生物所具有的出色飞行能力,为人造扑翼飞行器的设计工作提供了很好的参照。本文以鸟类的扑翼飞行为研究背景,针对简化的二维S1223翼型的刚性俯仰-沉浮运动,对其非定常气动力特性进行了数值研究。研究采用了动态混合网格技术以及非定常数值计算方法。为了提高动态混合网格的变形能力,采用了基于径向基函数的插值方法求解空间点的位移,翼型整个俯仰-沉浮运动周期内计算网格均维持了较好的质量,没有发生网格重构。非定常算法方面,通过约束单元边界面的法向速度从而满足了运动网格下几何守恒律的要求。空间离散采用了二阶的有限体积格式,时间离散则采用了双时间步和BLU-SGS相结合的隐式时间推进策略。计算得到了不同下拍时间、不同拍动角等条件下的升力、推力以及能耗,对其升力、推力产生机制进行了分析,并通过对气动力以及流场进行对比,分析了各拍动参数的影响。计算结果表明,翼型自身的"静态因素"是其产生升力的主要原因,非定常流动对增加升力起到了促进作用,而下拍时间、拍动角等运动参数对翼型的气动性能影响较大。当下拍时间占到整个拍动周期的约65%-70%时,单位能耗下的时均升力最大,该结论和观测数据较为一致。此外,通过对比分析得到了一组具有较好气动特性的拍动角参数,为后续针对三维问题的研究提供了参考。Flapping-wing micro air vehicle(F M A V)is one of the most directions of future aviation.The bird or insect in nature possess the advanced ability of flying because of thousands of years?evolution,so the study of their flight kinematics as well as flow mechanism can greatly contribute to the development of FM A V.To investigate the unsteady aerodynamic mechanism of flapping wing,simplified plunging/pitching motion of a rigid2-D SI223airfoil is firstly taken into consideration.Numerical method is based on the hybrid dynamic mesh technique and unsteady flow solver.To improve the moving ability of dynamic radius basis function is used to calculate the displacement of volume nodes.For unsteady flow solver on moving m e sh,geometric conservation law is satisfied by constraining the normal velocity of cell surface.Second-order finite volume method is used.Dual-time stepping method and BLU-SGS implicit scheme are adopted for time marching.T he unsteady lifts?thrusts as well as power consum ptions with different flapping param eters are abtained.The flow mechanism for lift and thrust is studied.T he influence of down-stroke time ratio and stroke angle is analyzed,which would greatly influence the aerodynamic performance and the power consumption.Numerical results show that the'static effect?of the airfoil plays the main role for litt generation.Meanwhile,the unsteady flow induced by the plunging/pitching motion can enhance the lift by weakening the flow separation and increasing the equivalent angle of attack.The maximum litt per be got when down-stroke time takes about65%-70%of the whole stroke cycle,which observation data.Further,a set of appropriate flapping angles are specified based on these analyses,which would greatly contribute to the realistic3-D simulations in the future.

关 键 词：鸟类扑翼 动态混合网格 非定常流动 RBF动网格方法 几何守恒律 

分 类 号：V211.3[航空宇航科学与技术—航空宇航推进理论与工程]